Could be a timer, yeah. Although it has two extra pins that function as a kind of Jack detector.I'm sticking with the jack board is nothing but 2 analog to Pwm converters based on a 555 type timer, a 10 v ( control signal from say apex) bypass to the next light and a 24 v line to power the add on controller.
Which chip on there do you think is a microcontroller?
There should be one on the push button board though.
Voltage regulator is to change 24v to what the 555 needs
Large resistor to limit 24c current.
Scroll back and you will find some pictures on page 2 where I annotated the pins. That’s the microcontroller/timer IC. And no, it doesn’t have markings.
It’s not quite as easy though. Image a 0V signal. How would the main board know that a Jack is connected ?
Voltage regulator is 5V, as we have determined. The large 2k resistor is mostly a sense resistor. When it shorts, it deactivates the pMOSFET supplying the 24V.